froth floatation

Copper from deep in the ground. SL M2.

Five stages:• Open Pit mining

• Pit crusher 0.6% Cu

• Froth floatation 30% Cu

• Smelting 90.4% Cu

• Electrolytic refining 99.98% Cu

chalcopyrite

azurite

malachite

CuFeS2 = chalcopyrite.

% Cu in pure chalcopyrite?

% by mass = mass of element in 1 mole of compound x 100

Mr of compound

CuFeS2

Mr = 64+56+32+32 = 184

% by mass = 64 x 100 = 35%

184

Open Pit mining.Bingham Canyon

Low grade copper

Quantities huge

Shavings tested

Dynamite used

Waste to tips

Open Pit mining.

•Noisy

•Dusty

•Leaves Open Pits

•Waste tips.

Pit crusher

Pit crusher

0.6% Cu

2.5cm pieces

Froth Floatation

Froth Floatation

Collector (oil) molecules attach themselves to the chalcopyrite grains.

The grains are now water-repellent.

Air bubbles attract the grains.

Froth produced and is pumped away to smelter.

•Detergent

•Oil

•Water

•Tailings

0.6%

30%concentrating

Smelting• First stage involves

– Silica– Oxygen– Concentrate

• Cu2S made

•Most important stage involves Cu2S / air / furnace

•Cu2S(l) + O2(g) 2Cu(l) + SO2(g)

Cu2S + O2 2Cu + SO2

0 -2

-2 +4

+1 0

O

S

Cu

Oxidised or reduced?

reduced

oxidised

reduced

What mass of copper could be obtained by reducing 1kg of copper (I) sulphide?

Cu2S + O2 2Cu + SO2

What mass of copper could be obtained by reducing 1kg of copper (I) sulphide?

160 128

Moles in

1kg

1 mol 2 mol

Mass in question

Mass in

Underline

160 160

0.800kg

Smelting

Sulphur dioxide made.

30% 99.4%

Acid rain

Lakes

Trees

H2SO4

Electrolytic Refining99.4% 99.98%

The copper anodes are already 99.4% copper!

The copper cathodes will be 99.98% copper!

e-e-Cu

e- e-

Anode + - Cathode

Cu2+

Cu2+Cu

Cu

Cu2+

CuCu2+

e-e-Cu

e- e-

Anode + - Cathode

Cu2+Cu

Cu

Cu2+

CuCu2+

•Describe what is happening at the anode.

•Write an equation.

•Is this oxidation or reduction?

e-e-Cu

e- e-

Anode + - Cathode

Cu2+

Cu2+Cu

Cu

Cu2+

CuCu2+

•Describe what is happening at the cathode.



e-e-Cu

e- e-

Anode + - Cathode

Cu2+Cu

Cu

Cu2+

CuCu2+


Cu(s) Cu2+(aq) + 2e-


Oxidation

e-e-Cu

e- e-

Anode + - Cathode

Cu2+

Cu2+Cu

Cu

Cu2+

CuCu2+

•Write an equation.Cu2+(aq) + 2e- Cu(s)


Reduction

Five stages:• Open Pit mining

• Pit crusher

• Froth floatation

• Smelting

• Electrolytic refining

froth floatation

Technology